Chennai, March 27 : The Tamil Nadu have stepped up surveillance after receiving inputs from Central agencies and the state intelligence wing on the possibility of certain foreign groups smuggling drugs into the state through the sea route. The police are on alert near the Ramanathapuram area as there were specific inputs that this route would be used by certain international groups affiliated to former LTTE associates. The Chennai police have unearthed a major drug network a few days ago. Methamphetamine valued at Rs 9 crore was seized. Two persons, Rajkumar (35) and Chandrashekar (42) were arrested. Sources in the police told IANS that the duo during questioning had provided information about more such gangs active in the state, and that the drugs were reaching Tamil Nadu through the coastal route. It may be recalled that the Central intelligence agencies had earlier given inputs on the certain former cadres of the now defunct LTTE trying to revive the organisation and raising funds for it. The Tamil Nadu police have stepped up surveillance on the sea to prevent any boats reaching the coasts of Ramanathapuram or Nagapattinam during late hours. /IANS